Sedimentary Or Metamorphic (Base Substrate)

Mica Schist with Iron Staining

Muscovite/Biotite Schist

Muscovite Schist

KAl2(AlSi3O10)(OH)2 (Muscovite) in Schist Matrix

Mica Schist

Mica Schist (Quartz-Mica Metamorphic Rock)

Green calcite (probable)

Calcite, calcium carbonate (CaCO₃)

Polished greenstone pebble

Likely serpentinite (serpentine-group minerals); identification from appearance alone is uncertain

Mica-rich Sandstone or Micaceous Schist Weathering

Micaceous Schist (Muscovite-Quartz composition)

Weathered mica-rich rock, likely mica schist

Mica schist, composed mainly of muscovite and/or biotite with quartz and feldspar

Oyster shell fragment

Ostreidae shell; primarily calcite (CaCO₃)

Pyrite

Iron Disulfide (FeS2)

Black Spinel

Magnesium Aluminum Oxide (MgAl2O4)

Garnet-Bearing Gneiss

Almandine-Garnet Gneiss

Beach Pebble (Quartzite / Sandstone)

Quartz-rich sedimentary or metamorphic rock pebble

Sandstone (Micaceous Sandstone)

Arenite (SiO2 with KAl2(AlSi3O10)(OH)2 inclusions)

Muscovite mica schist

Muscovite-rich schist; predominantly muscovite mica (KAl₂(AlSi₃O₁₀)(OH)₂) with quartz and minor iron oxides

Likely raw mica-bearing metamorphic rock or mineral fragment

Tentatively biotite schist; visually similar dark mica-rich material

Muscovite Schist

Muscovite (KAl2(AlSi3O10)(OH)2) in Schist

Tree Agate

Cryptocrystalline quartz (Chalcedony), SiO2

Mica Schist

Schist (Muscovite-Quartz Schist)

Mica Schist

Mica Schist

Likely chlorite-bearing schist (possibly greenschist)

Chlorite–quartz–mica schist; commonly contains muscovite/biotite and feldspar

Quartz with Mica / Chlorite Inclusion

Silicon Dioxide (SiO2) with Phyllosilicate minerals

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Likely biotite mica in a host rock

Biotite, a dark mica-group mineral; composition varies, broadly K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂

Greenstone

Metamorphosed Mafic Igneous Rock

Muscovite Mica

Muscovite (Potassium Aluminum Silicate Hydroxide Fluoride), KAl2(AlSi3O10)(OH,F)2

Mica-rich schist (likely quartz-mica schist)

Quartz–mica schist, commonly containing muscovite and/or biotite with quartz and feldspar

Red coral (polished coral beads)

Corallium spp.; chiefly calcium carbonate (CaCO₃, calcite)

Schist (Micaceous Schist)

Schist (comprising Muscovite/Biotite mica, Quartz, and Feldspar)

Biotite mica schist

Mica schist, chiefly biotite (K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂) with quartz and feldspar

Biotite mica schist fragment

Biotite-rich mica schist; chiefly biotite K(Mg,Fe)3AlSi3O10(F,OH)2 with quartz and feldspar

Weathered mica-rich schist

Mica schist, likely muscovite–quartz schist

Polished gemstone tower assortment

Primarily quartz varieties and simulants; apparent amethyst (SiO₂), rose quartz (SiO₂), clear quartz (SiO₂), fluorite (CaF₂), sodalite, malachite, and possibly dyed or composite stones

Small gold-colored mineral crystal, likely pyrite

Pyrite (FeS₂), tentatively; native gold is a less likely alternative

Sandstone pebble

Sandstone (mainly Quartz, SiO2)

Milky Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Mica Schist (with Golden/Biotite inclusions)

K(Mg,Fe)3AlSi3O10(F,OH)2 (Biotite), KAl2(AlSi3O10)(F,OH)2 (Muscovite)

Limonite after Pyrite (Prophecy Stone or Ironstone Concretion)

Goethite/Limonite pseudomorph after Pyrite/Marcasite (FeO(OH)·nH2O)

Gneiss

Gneiss (High-grade metamorphic rock)

Quartz on Schist

Silicon Dioxide (SiO2) on Foliated Metamorphic Rock

Likely slate fragment

Slate, a fine-grained metamorphic rock composed mainly of mica-group minerals and quartz

Iron-Stained Quartzite

Recrystallized Meta-Quartzite (primarily SiO2)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)